1. Field of the Invention
The present invention relates to a backpack, and more particularly to a backpack with a shoulder strap height adjustment unit which is guided by a rail frame installed on a back surface of the backpack to adjust the height of shoulder straps with respect to the back surface of the backpack so as to allow a user to wear the backpack while adjusting the height of the shoulder straps according to the physical characteristics of the user.
2. Description of the Related Art
In general, a backpack is provided with various types of straps used when a user wears the backpack. That is, as shown in FIG. 1, a conventional backpack 1 includes shoulder straps 2 worn over the shoulders of the user, waist straps 3 fastened across the waist of the user, and chest straps 4 fastened across the chest of the user.
The shoulder straps 2 serve to support the backpack 1, and the waist straps 3 and the chest straps 4 serve to prevent the backpack 1 from tilting backwards and to more stably adhere the backpack 1 to the body of the user so as to prevent the backpack 1 from swinging while keeping a state in which the user stably wears the backpack 1.
The shoulder straps 2, which are the principle components in supporting the backpack 1, do not have a length adjustment function and are fixed to the same position of the back surface of any backpack, thus being worn by users in the same shape regardless of physical characteristics of the users.
That is, the upper ends of the shoulder straps 2 are sewn to the upper end of the back surface of the backpack 1, and the lower ends of the shoulder straps 2 are connected to straps 8 sewn to the lower end of the back surface of the backpack 1 such that the length of the shoulder straps 2 is adjustable. Therefore, a user has no option but to use the backpack 1 in a state in which the upper ends of the shoulder straps 2 are fixed to the upper end of the backpack 1 regardless of amounts or sizes of articles received in the backpack 1 or a size of the backpack 1.
If the user wears the backpack 1 in which the upper ends of the shoulder straps 2 are simply fixed in such a manner, the lower end of the backpack 1 may ride excessively low or high according to the body size of the user and thus the user cannot stably wear the backpack 1. Therefore, when the backpack 1 is worn for a long period of time or when mountain claiming, such an unstable worn state of the backpack 1 provides considerable fatigue and inconvenience to the user.
For example, if a short user wears the backpack 1, the backpack 1 is located at a position below the waist of the user, and thus the backpack 1 may cause unpleasant contact with the body of the user and provide inconvenience to the user due to swinging of the lower end of the backpack 1 during walking and the user may easily feel tired. On the other hand, if a tall user wears the backpack 1, the backpack 1 is located at a position above the waist of the user, and thus the backpack 1 may be out of balance due to upward movement of the center of gravity and the user may easily feel tired or stable walking of the user may be difficult.
Although the waist straps 3 and the chest straps 4 assist the backpack 1 to be in close contact with the body of the user, the waist straps 3 and the chest straps 4 cannot adjust the center of gravity, thus being incapable of solving the unbalanced state of the backpack 1.
Accordingly, proper adjustment of a position of the shoulder straps 2 of the backpack 1 during contact between the backpack 1 and the body of the user is required.